Proteins are essential nutrients for animals and humans. Most livestock and humans get a large part of the necessary proteins from vegetable protein sources. Important vegetable protein sources are e.g. oilseed crops, legumes and cereals. When e.g. soybean meal is included in the feed of mono-gastric animals such as pigs and poultry, a significant proportion of the soybean meal solids is not digested. E.g., apparent ileal protein digestibilities of only 77% and 84% have been reported in piglets and growing pigs, respectively.
Indeed, cereal grains, pulses, and tubers contain a number of anti-nutritional factors and potential allergens such as alpha-amylase/trypsin inhibitors present in wheat, barley and related cereals, or soybean trypsin inhibitors (Kunitz type inhibitors and/or Bowman-Birk inhibitors) which prevent optimal growth performance, may alter health of the animal, and lead to an unnecessary release of nitrogen in the environment.
Most plant storage organs such as seeds and tubers contain 1-10% of their total proteins as protease inhibitors with different biochemical and structural properties inhibiting different types of proteases. Protein inhibitors are classified based on the type of enzyme they inhibit: serine protease inhibitors, cysteine protease inhibitors, aspartic protease inhibitors, or metallocarboxy-protease inhibitors.
Plant allergens are a widespread group of plant proteins comprising cupin and prolamin super families as well as proteinaceous molecules of the plant defense system. The prolamin superfamily includes several important types of allergens of legumes, tree nuts, cereals, fruits, and vegetables, and the cereal alpha-amylase and protease inhibitors. Based on structural similarity, proteinaceous alpha-amylase inhibitors with plant origin are usually classified in six families including lectin-like, knottin-like, CM-proteins, Kunitz-like, c-purothionin-like, and thaumatin-like (Richardson, 1991). CM (Chloroform-methanol)-proteins are a large protein family from cereal seeds containing 120 to 160 amino acid residues and five disulfide bonds. They show a typical double-headed alpha-amylase/trypsin domain. This feature makes it possible that they inhibit the activity of alpha-amylase and trypsin-like enzymes. The alpha-amylase inhibitor 0.19 is one of the most studied inhibitor of this family; it has a broad specificity, and inhibits alpha-amylases from insects, birds and mammals. Soybean trypsin inhibitor (Kunitz type) has first been discovered by Kunitz in 1945.
WO 2011/137322 recently disclosed that members of the alpha-amylase/trypsin inhibitor family contained in wheat and related cereals are strong inducers of innate immune response in human intestine. In farm animal, this effect translates into suboptimal animal performance, reduced digestibility, and intestinal inflammation.
The use of exogenous enzymes in animal feed has been one of the most promising strategies for improving animal performance as summarized in a recent review by Munir and Maqsood, EJFA, 2013, 25:66-80.
WO 2011/137322 disclosed the use of antibodies against alpha-amylase CM 3 in order to treat celiac patients or food compositions, and considers the use of protease as an alternative. However, it is silent with regard to a specific enzyme to efficiently hydrolyze alpha-amylase/trypsin inhibitors or Soybean trypsin inhibitors in the gastrointestinal tract of animals with the aim to improve digestibility and animal performance.
It would be desirable to provide a safe, effective and cost competitive way to degrade alpha-amylase/trypsin inhibitors or cereals as well as trypsin inhibitors of pulses, oilseeds, and tubers in the gastro intestinal tract of farm animals fed compositions comprising such inhibitors in order to reduce intestinal inflammation, to reduce nitrogen excretion, and to improve animal performance.